Why is my Z10's battery powering down at 20?

My z10 auto shutdown when its battery reaches 20% after update 10.2.1.3247 or later. I had tried more ideas but this could not be resolve my problem please told perfect solution for this?? I am very depressed???

1. Turn off your device.
2. Remove the battery.
3. Plug the charger to your device. It should be plugged to a wall socket on the other end.
4. Your device should lit up red LED.
5. Remove the charger, put back the battery, turn ON your device.
6. It should now display the correct battery value.

1. Turn off your device.
2. Remove the battery.
3. Plug the charger to your device. It should be plugged to a wall socket on the other end.
4. Your device should lit up red LED.
5. Remove the charger, put back the battery, turn ON your device.
6. It should now display the correct battery value.